Idiopathic Pulmonary Fibrosis (IPF) is a progressive lethal lung disease characterized by persistent myofibroblast differentiation and excessive synthesis of extracellular matrix (ECM). Myofibroblasts produce increased contraction forces that are transmitted from the cytoskeleton to the surrounding ECM by transmembrane integrins. This results in activation of the ECM-bound latent transforming growth factor (TGF)-(1, the most potent fibrogenic cytokine. Evidence suggests that such mechano-induced latent TGF-(1 activation is essential for maintaining myofibroblast differentiation. Understanding of the mechanisms involved in regulation of mechano-induced TGF-(1 activation and myofibroblast differentiation is of both scientific significance and clinical interest. Thy-1, a glycosyl phosphatidylinositol (GPI)-linked cell surface protein, has been shown to prevent lung myofibroblast differentiation and fibrosis. The mechanisms underlying Thy-1 anti-fibrotic effect are not clear. Preliminary data now show that lung fibroblasts expressing Thy-1 respond to fibroblast contraction with increased latent TGF-(1 activation and TGF-(1-dependent alpha-smooth muscle actin ((SMA) expression, whereas lung fibroblasts lacking Thy-1 expression do not. In this study, we hypothesize that Thy-1 regulates mechano-induced latent TGF-(1 activation and lung myofibroblast differentiation. Specific Aims in the proposed studies are: 1) To determine whether Thy-1 regulates fibroblast contraction force formation and force-induced, TGF-(1-dependent myofibroblast differentiation. We will employ a deformable silicone substrate wrinkling assay to measure fibroblast contractility. We will build a device to test the role of Thy-1 at the tissue level by using lung parenchymal strips isolated from Thy-1 null and wild-type mice. 2) To determine whether Thy-1-integrin interactions interrupt fibroblast mechanotransduction, abrogating mechanical force-induced latent TGF-(1 activation and lung myofibroblast differentiation. We will generate a mutated Thy-1 in which the capability of Thy-1 binding to integrins is disrupted to test our hypothesis. Our studies are aimed at understanding the molecular mechanisms involved in regulation of mechano-induced latent TGF-(1 activation and lung myofibroblast differentiation. The goal is to identify molecular targets for developing novel therapeutic interventions for treatment of IPF by blocking lung myofibroblast differentiation. PUBLIC HEALTH RELEVANCE: Idiopathic pulmonary fibrosis (IPF) is a progressive, lethal fibrotic lung disease with no effective therapies. The proposed studies will explore the molecular mechanisms involved in the pathogenesis of lung fibrosis. Our goal is to develop novel therapeutic interventions for IPF treatment.